In the arid regions of the Earth, desiccated cyanobacterial mats constitute the predominant biological characteristic. Desiccated cyanobacteria’s reaction to rehydration in terrestrial settings has been extensively studied, but less is known about their behaviour in marine systems. We investigated this reaction in a dehydrated microbial mat from Exmouth Gulf, Australia, using high temporal resolution hyperspectral imaging, liquid chromatography, pulse-amplitude fluorometry, oxygen microsensors, and confocal laser microscopy. Chlorophyll a concentrations increased 2 fold–5 fold over the first 15 minutes after rehydration, and cyanobacterial photosynthesis resumed. We speculate that resynthesis from a precursor stored in dried cyanobacteria is responsible for this sudden surge in chlorophyll a, even if the exact mechanism is still unknown. The reactivated cyanobacteria moved toward the mat surface during the following phase (15 minutes to 48 hours), which coupled with a progressive rise in chlorophyll, caused a further increase in photosynthesis. We come to the conclusion that cyanobacteria from dried mats of both terrestrial and marine origins exhibit the same reaction, which involves an increase in chlorophyll a and a recovery of photosynthetic activity within minutes following rehydration. But the reaction of upward migration and the mechanism that sets it off seem to be mat-specific and probably dependent on other elements. In the arid regions of the Earth, desiccated cyanobacterial mats constitute the predominant biological characteristic. Desiccated cyanobacteria’s reaction to rehydration in terrestrial settings has been extensively studied, but less is known about their behaviour in marine systems. We investigated this reaction in a dehydrated microbial mat from Exmouth Gulf, Australia, using high temporal resolution hyperspectral imaging, liquid chromatography, pulse-amplitude fluorometry, oxygen microsensors, and confocal laser microscopy. Chlorophyll a concentrations increased 2 fold–5 fold over the first 15 minutes after rehydration, and cyanobacterial photosynthesis resumed. We speculate that resynthesis from a precursor stored in dried cyanobacteria is responsible for this sudden surge in chlorophyll a, even if the exact mechanism is still.
